MEXICO CITY — Of the half-dozen pieces that form Tania Bruguera’s series “Tatlin’s Whisper,” the one that the Cuban government silenced may have resounded most.

An attempt by Ms. Bruguera, a New York-based Cuban artist, to stage an open-mike performance in Revolution Square in Havana on Dec. 30 prompted a burst of news coverage. Ms. Bruguera, 46, who was arrested before the performance but has been released and is awaiting possible public disorder charges, has become an art world cause célèbre.

As the United States and Cuba begin talks to restore diplomatic relations, the “Bruguera affair,” as some are calling it, is a reminder of the limits of expression in Cuba and the hope among artists and activists that the détente will result not only in economic benefits but also broader rights. It has also blurred the boundaries between art and political activism, challenging the state’s control over cultural spaces.

“In a sense it was a test,” Ms. Bruguera said of her bid to stage the work, “Tatlin’s Whisper #6,” in which Cubans would express their desires for the country’s future.Speaking by telephone from Havana this week, she said of Cuban authorities, “Now I see they would never have allowed it.”

Cuba is, in some respects, like a giant schoolyard, where some citizens try to push the envelope as much as possible without paternalistic authorities clamping down. Visual artists, writers, filmmakers, theater directors and musicians are constantly nudging the changeable line between what can and cannot be said. Every few months, it seems, one crosses the line and is chastised.

Robertico Carcassés was temporarily barred from government-run music spaces in 2013 after he called for free elections during a nationally televised concert. In September, a show called “Utopias y Disidencias” by Pedro Pablo Oliva was abruptly called off. Mr. Oliva, a prominent Cuban painter from Pinar del Río, was ostracized by provincial officials after he criticized harassment of dissidents four years ago.

Notwithstanding the showdown over “Tatlin’s Whisper,” the space for expression has grown significantly since the early days of the revolution, when Fidel Castro said: “What are the rights of writers and artists, revolutionary or not revolutionary? Within the revolution, everything; against the revolution, no right.”

President Raúl Castro is more open to debate than his older brother, Fidel. And even the extremely limited Internet access in Cuba has made it hard for the government to control all areas of media and culture. Many Cubans surreptitiously receive satellite television signals from the United States and pass movies, music and articles around on devices. A community of bloggers has emerged, some highly critical.

While the state still produces or vets virtually all Cuban television, radio and print-media content, for example, there is an increasingly audacious repertoire of theater and film. Yet the boundaries of expression remain capricious, and the dance with the censors involves a subtle understanding of what can be said where and by whom.“You never know how far you can go,” said Leonardo Padura, a well-known Cuban novelist, whose popular detective novels are a blistering study of the hardships and shady dealings of daily life in Cuba. He added, “Sometimes it seems as if spaces open and then close again.”

Artists and activists are skeptical that this will change, even with the diplomatic thaw. Just last month, “Return to Ithaca,” a film by the French director Laurent Cantet, based on a story by Mr. Padura about a returning Cuban exile, was pulled, without explanation, from the International Festival of New Latin American Cinema in Havana. Mr. Padura, who helped write the screenplay, would not discuss the decision, but in an open letter, a group of filmmakers condemned what they called a “serious, unnecessary and outdated act of censorship.”

For some who cross the limits, punishment can be harsh. Danilo Maldonado Machado, a graffiti artist known as El Sexto, has been in police detention since Dec. 25, when he tried to transport two pigs whose flanks were emblazoned with the names Fidel and Raúl that he intended to use in a performance.

Boris González Arenas, a professor at the International Film and Television School near Havana who was detained for three days after he went to Revolution Square for “Tatlin’s Whisper,” was fired two days later, ostensibly for publishing articles “against the Cuban State.”

Censorship is, at times, as much about where a work is shown as the work itself. The state-run National Council of Visual Arts suggested that Mr. Oliva first put on his “Utopias y Disidencias” show, a series of vignettes about a Candide-like Cuban, in Havana, perhaps because the capital is more open-minded or because officials there bear him no personal grudge; he refused.

Enrique Del Risco, a Cuban academic who lectures at the Spanish department of New York University, said that what troubled authorities most about Ms. Bruguera’s open-mike performance was probably not what Cubans might have said there but that they would have said it on hallowed ground, a vast square that is used for political rallies and overlooked by murals of revolutionary heroes.

Ms. Bruguera was arrested before the performance could take place, as were dozens of people who went to Revolution Square to take part. The artist, who has since been detained and released two more times, has had her passport confiscated and says that authorities offered to return it if she promised not to return to Cuba.In an interview published in La Jiribilla, a state-run cultural newspaper, Rubén del Valle Lantarón, president of the National Council of Visual Arts, said that he had offered Ms. Bruguera alternative spaces, such as a factory, universities, a bus stop or a fruit market — options that he said she turned down. Ms. Bruguera said she rejected places where officials could restrict participation and suggested, as an alternative to Revolution Square, a small square in Old Havana. Officials refused, she said.Mr. del Valle described Ms. Bruguera’s performance as a “reality show” undertaken “under a lot of external pressures” from anti-Castro exiles — a charge Ms. Bruguera dismissed.

Artists and intellectuals, in Cuba and abroad, condemned the government’s crackdown, and more than 2,200 have signed a petition calling for Ms. Bruguera’s freedom. The episode led to a heated exchange among intellectuals about whether Ms. Bruguera’s feat was a brave stand for free expression or an ill-timed publicity stunt.The debate exposed the complex dynamics within a sphere whose artists preserve a delicate entente with cultural authorities. These artists sometimes resent gestures they see as grandstanding, especially from Cubans or others who do not live in the country.

Lázaro Saavedra, one of a few artists in Cuba who signed the petition, wrote on a blog that the Bruguera incident was “another point on her artistic curriculum rather than a gain in terms of civil rights.” Mr. Saavedra, whose works, in different media, poke fun at Cubans’ paranoia, ideological hypocrisy and the artistic process, wrote that those struggling for Cubans’ rights “would have loved Tania had she been close during moments of repression.”

Ms. Bruguera defended the timing of the piece and her right to protest, as a Cuban.The piece was “political timing specific,” she added, in that it worked in a particular political moment.“Everything that happened — from the day that we formed the platform, is a performance,” she said. “And it turned out different from what I expected.”The performance includes Cuban authorities and their supporters, who, Ms. Bruguera said, have produced their own piece of “theater,” suggesting she is sponsored by the Central Intelligence Agency, a charge she also denied.

Mr. Del Risco, the Cuban academic, said Ms. Bruguera’s participatory work, which plays with the barriers between art and reality, challenged the Cuban government’s predilection for well-defined space.“What Tania did is to break a hole between two spaces that are supposed to be kept separate — art and reality, art and the people, art and politics,” Mr. Del Risco said.

He hopes American officials will continue to press for freedoms as they negotiate new diplomatic and economic relations.“The United States has too much faith in the power of the economy and of tourism to bring political change,” he said. “Just because the two countries have contact, I don’t think there will be some magical opening.”